Arid zone island hopping: the impact of dispersal on endemism in hydraenid beetles (Coleoptera: Hydraenidae) found in isolated desert springs

Abstract

AbstractThe Great Artesian Basin (GAB) provides a reliable source of water in the form of isolated freshwater springs to an otherwise arid Australian landscape. Across this landscape, dispersal potential relative to the distribution of freshwater springs can influence diversification and endemism of associated invertebrate fauna. Many aquatic taxa inhabit these springs, but best known are the poorly dispersing short‐range endemic, obligate aquatic taxa including crustaceans, hydrobiid snails and desert goby fish. Long distance dispersal potential and its impact on diversification and endemism have not previously been examined in spring‐associated beetles, in particular the family Hydraenidae, which are found in many springs. Our aims were to examine phylogenetic relationships and identify possible endemism among individuals species of Ochthebius (Gymnochthebius) from GAB springs and to use inter‐ and intra‐specific phylogeographic structure and geographic distributions to infer dispersal capability. We sequence done mitochondrial gene for 125 individuals from three known species of Ochthebius (Gymnochthebius) Orchymont, 1943, that are endemic to the arid zone and the GAB springs. Overall, we confirmed the reciprocal monophyly of the three species as well as identifying two new spring clades of Ochthebius (Gymnochthebius). The placement of a species from Kangaroo Island within the phylogenetic tree indicated that the GAB springs species are not monophyletic and that multiple origins of Ochthebius (Gymnochthebius) have occurred into the GAB springs. Some species had shared haplotypes between spring complexes >195 km apart, suggesting significant dispersal, while other species are apparently restricted to a single spring complex, indicating a possible disparity in the dispersal ability among species. Population analysis of the most widespread species, Ochthebius (Gymnochthebius) fontinalis Perkins, 2005, revealed significant geographic and phylogenetic structure with evidence of many new haplotypes. The Ochthebius (Gymnochthebius) species examined here have a complex phylogeographic structure with evidence of endemism, but also high gene flow between spring groups, indicating that dispersal potential is varied.